1. Field of the Invention
This invention relates to an ophthalmologic apparatus which can compound the result of the measurement of the field of view of an eye to be examined and relates a corresponding eye fundus image, and to a method of compounding the image of the eye to be examined.
2. Related Background Art
Perimeters have heretofore been widely used to measure the fields of view of examinees. The outline of such perimeters will hereinafter be described with reference to FIG. 11 of the accompanying drawings. FIG. 11 illustrates a perimeter and its measuring state. The perimeter is fixedly constructed on a table 1 so that the inner surface of a substantially hemispherical dome 2 faces an examinee A and the outer surface of the dome 2 faces an examiner B. The examinee A has his face fixed by a fixing member 3 provided on the inner surface of the dome. The examinee A responds as to whether he could recognize an index presented successively on the inner surface while watching a fixation target on the inner surface of the dome 2. The examiner presents an index on the inner surface of the dome 2 while monitoring the gazing point of the examinee A by means of a loupe 4 provided on the outer surface side of the dome 2, and manually records the result of the response on recording paper 5 disposed on the table 1. FIG. 12 shows an example of the format of a view field chart on the recording paper 5, and the result of the response is plotted by the help of the view field chart printed on the recording paper 5, for example, the view field chart C comprising a plurality of concentric circles and four axes in directions to divide these concentric circles into eight parts. Besides this method, use has been made of a method using a TV monitor, instead of the recording paper 5, to plot measuring points on a view field chart on the TV monitor.
Heretofore, when determining the correspondence between this output result and the fundus of the eye to be examined, the examiner had to compare the photograph of the eye fundus with view field data with his eyes on the basis of the information of the center of the field of view and the blind spot portion of the field of view this was inefficient.
On the other hand, there is also known an eye fundus perimeter in which the view field measuring function is added to the eye fundus photographing function and a photographing output having the result of view field measurement imprinted on an eye fundus image is obtained. This perimeter is such that infrared light is applied to an eye to be examined and the examiner moves the index of visible light while observing the infrared eye fundus image of the eye fundus image on a TV monitor, and plots by means of a pen on a light-transmitting recording plate mounted in the apparatus or plots by perforating recording paper, in accordance with the examinee's response, and the plot image, together with the infrared eye fundus image, is displayed on the TV monitor and simultaneously with the photographing of the fundus of the eye, a final plot image is imprinted on the photograph. This is described in detail, for example, in U.S. Pat. No. 4,279,478.
However, in this prior-art eye fundus perimeter, the eye fundus image capable of being displayed is only the eye fundus image in real time during the view field measurement, and the past eye fundus images or the like cannot be displayed. That is, for example, even if there is a desire to measure the field of view while observing the eye fundus image before a disease has been cured, it is impossible with such a the prior-art type device.
Also, the eye fundus image produced by infrared light is not clear and further, infrared light penetrates more deeply into the interior of the fundus of the eye than visible light and therefore, the resultant infrared image is an image of the deeper portion of the fundus than the visible image, and this has led to the problem that such image differs from the outermost eye fundus image.
Also, during long-time view field measurement, it has been necessary to apply infrared light to an eye to be examined.